Weekly and Holiday-Related Patterns of Panic Attacks in Panic Disorder: A Population-Based Study

et al. (2014) Weekly and Holiday-Related Patterns of Panic Attacks in Panic Disorder: A Population- Based Study. PLoS ONE 9(7): e100913. doi:10.1371/journal.pone.0100913 Weekly and Holiday-Related Patterns of Panic Attacks in Panic Disorder: A Population-Based Study Li-Ting Kao 0 Sudha Xirasagar 0 Kuo-Hsuan Chung 0 Herng-Ching Lin 0 Shih-Ping Liu 0 Shiu-Dong Chung 0 Robert Stewart, Institute of Psychiatry, United Kingdom 0 1 Graduate Institute of Life Science, National Defense Medical Center , Taipei, Taiwan , 2 Sleep Research Center, Taipei Medical University Hospital , Taipei, Taiwan , 3 Arnold School of Public Health, Department of Health Services Policy and Management, University of South Carolina, Columbia, South Carolina, United States of America, 4 Taipei Medical University Hospital, Department of Psychiatry, Taipei, Taiwan, 5 Taipei Medical University, School of Medicine, Department of Psychiatry, Taipei, Taiwan, 6 Taipei Medical University, School of Health Care Administration , Taipei, Taiwan , 7 Department of Urology, National Taiwan University Hospital and College of Medicine , Taipei, Taiwan , 8 Division of Urology, Department of Surgery, Far Eastern Memorial Hospital , Ban Ciao, Taipei, Taiwan , 9 School of Medicine, Fu-Jen Catholic University , New Taipei City , Taiwan Background: While chronobiological studies have reported seasonal variation in panic attacks (PA) episodes, information on the timing of PA by week-days may enable better understanding of the triggers of PA episodes and thereby provide pointers for suitable interventional approaches to minimize PA attacks. This study investigated weekly variation in potential PA admissions including associations with holidays using a population-based longitudinal, administrative claims-based dataset in an Asian population. Methods: This study used ambulatory care data from the ''Longitudinal Health Insurance Database 2000. We identified 993 patients with panic disorder (PD), and they had 4228 emergency room (ER) admissions for potential PA in a 3-year period between 1 January 2009 and 31 December 2011. One-way analysis of variance (ANOVA) was used to examine associations between the potential PA admissions and holidays/weekend days/work-days of the week. Results: The daily mean number of potential PA admissions was 3.96 (standard deviation 2.05). One-way ANOVA showed significant differences in potential PA admissions by holiday and day of the week (p,0.001). Daily frequencies showed a trough on Wednesday-Thursday, followed by a sharp increase on Saturday and a peak on Sunday. Potential PA admissions were higher than the daily mean for the sample patients by 29.4% and 22.1%, respectively on Sundays and holidays. Furthermore, the weekly variations were similar for females and males, although females always had higher potential PA admissions on both weekdays and holidays than the males. Conclusions: We found that potential PA admissions among persons with PD varied systematically by day of the week, with a significant peak on weekends and holidays. - . These authors contributed equally to this work. " These authors also contributed equally to this work. Panic disorder (PD) is a widely prevalent severe anxiety disorders characterized by recurrent and unexpected panic attacks (PA) [1]. PA is generally characterized by intense fear or discomfort with least four somatic or cognitive symptoms, sometimes accompanied by agoraphobia [2,3]. In the United States, an estimated that 4.8% of the adult population is affected by PD over the lifetime with or without agoraphobia [4]. Studies show that PD is costly for patients and society due to increased use of medical resources and reduced work productivity [57]. Studies of temporal variations in PA episodes may provide pointers to the underlying etiological factors and may enable intervention approaches to minimize the severity and frequency of PA. The risk factors for PA remain unclear [5] despite studies suggesting possible associations with lifestyle [8,9], psychosocial [5,10], and environmental factors [8,10,11]. Chronobiological studies have reported seasonal variations in PA episodes [1012]. Studies from Australia and Japan indicate higher incidence in summer and winter [10,11]. However, very few studies on detailed temporal variation synchronous with the diurnal and weekly rhythms of peoples lives have been documented. A study from Finland reported that the diurnal and weekly rhythms of peoples lives are closely related to work and leisure times [13]. A finding of associations between PA onset and the day of the week may provide practical guidance on the context and factors that trigger a PA and thus provide pointers for research and intervention programs. This study investigated variations in potential PA admissions among persons with a PD diagnosis by day of the week using a population-based dataset in an Asian population. Data source This study used ambulatory care data from the Longitudinal Health Insurance Database 2000 (LHID2000) published by the National Health Research Institute (NHRI) of Taiwan. The LHID2000 consists of de-identified cumulative claims data on one million randomly selected enrollees of Taiwans National Health Insurance system designed to be representative of the total enrollee population as of December 2000. The LHID2000, which was open to the researchers in Taiwan, was available from the NHRI (http://nhird.nhri.org.tw/date_01.html). This study is based on de-identified secondary data from the LHID2000 released by the NHRI without restrictions for research purposes. As such it was exempted from full review by the Taipei Medical Universitys Internal Review Board (IRB) and is in compliance with the international ethical standards. Study Sample We identified all patients with a principal diagnosis of PD (ICD9-CM code 300.01) in the LHID2000 with an ambulatory psychiatric care treatment claim between January 2008 and December 2008 (n = 1,716). To ensure validity of diagnosis of study patients we included patients who had at least two PD diagnoses in ambulatory care claims of which at least one was made by a certified psychiatrist. We restricted our study to only those who had ever been admitted into an emergency room (ER) for potential PA between 1 January 2009 and 31 December 2011 for a study sample of 993 patients with PD. We defined potential PA if a PD patient admitted to an ER was diagnosed with a PA-relevant symptom such as dizziness/ giddiness, headache, hyperventilation, chest pain, palpitations, abdominal pain, and anxiety state without a definitive diagnosis of a related physical condition. We used symptoms identified in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria for PA [3,14]. Taiwan has a welldeveloped and well-distributed network of emergency medical services which is covered by NHI, which in turn provides medical care coverage to 99% of Taiwans citizens with a common bene (...truncated)